Hatz Biplane Association

Sheet 16 - Rear Gear Leg - Front Spar fitting. The strap that wraps around this assembly is drawn with two different dimensions. The strap extends along the bottom fuselage cross member and then makes a roughly 47 degree bend up towards the bushing for the spar attachment. From the point of that bend back along the cross member the side view measures 3 inches while the bottom view measures 4 inches. The 3 inch measurement seems to match the drawing of the fuselage bottom on sheet 11 which also shows this piece.

Update 3/15/16 - Got home yesterday and found my CB-1 plans had arrived so I can finally compare the two sets of plans. In looking at the CB-1 drawings, the 3 inch dimension appears to be the correct one.

Doug, I got caught by that one. One of mine is 3 inches and the other is 4, that should average out perfect.

I found that the sheet that depicts the windscreens has them reversed.

As Nick mentioned before, on sheet 14, in the lower right corner, the trim tab detail dimensions are about 2x what they should be. This whole page seems to leave a lot to your imagination.

I don't think that the plans show any bolts mounting the front of the horizontal stabilizers but there should be.

ssearle wrote:I found that the sheet that depicts the windscreens has them reversed.

Also, the lexan size required is messed up .

In the description of the Frame it reads " Windshield Frame .032 3003 Aluminum & 1/8" Lexan......

In View detail A-A it reads 3/16" Lexan.

Also, I just don't understand how the lower lips are formed based on the drawing either..... The lips I thought should be on the upper parts of the inside of the frames. I ordered mine from Makelan, but as of yet have not arrived. Hopefully, how they are made will be cleared up if and when I receive mine.

While I was doing the calculations for the compression tubes I came across a subtle error on the plans that is small enough that it probably won't affect a build. But it probably will cause some grief in building the wing.

If you look at the rib template drawing you will see that the rib has a slight upward curve at the bottom of the front spar. This isn't mentioned in the cross section of the front spar for either top or bottom wing. The slope of the bottom of the front spar is 1/32" of an inch from front to back and not level as shown on the plans. The ribs will fit, but there needs to be some fitting if you use the height of 4.842" as shown on the plans. Shave the spar down to 4.81 and the ribs will fit nicely with a slight gap at the back if the front spar.

However, the bottom of the front spar is about 1/16" higher than the rear spar because of the same slight curve in the bottom of the rib. All of the measurements for the compression tubes are from the bottom of the spars. That makes all the compression tubes misaligned by 1/16" from front spar to rear spar. If you put a level on the bottom of the rib, and then on the compression tube, they won't be the same.
The problem doesn't exist for the center section spars. The bottom of the spars are level as they sit on top of the 1/4" plywood floor. Detail A on drawing 04 shows the bottom of the plywood floor is blended to match the bottom of the wing at the front spar. So if you aligned the wing to match the center section, the hole for compression tube #1 on the front wing will be 1-11/16" from the bottom of the front spar.

mar.15.2017- I was putting my first wing together and took a picture of 1/32" gap on bottom of main spar. I didn't slant the bottom of the spar to match.

I believe the stationing for FSBW2 of Drawing 07 - Bottom Wing is incorrect. The stationing for the interplane strut hole should be 75.265 to match the hole on RSBW2. The distance between the two holes on FSBW2 is 1.01" (should be 1.0" I think but not the problem). But 75.265" - 1.0" + 0.385" (distance to lower hole) = 74.65"! not the 74.5" shown. All the stationing for FSBW2 is out by 0.15". RSBW2 can't move because of the compression tube so I moved FSBW2 0.15" outward. This also lines up the anti-torque tube slots correctly.

Sheet 22 Front/Rear Landing Wire Lug - Bottom End

When I tried to make these lugs the insert was too long for the outer strap.

From the dimensions on the other lugs which seem to work, the strap needs to be 2x the length of the insert plus and extra 1.33" to wrap around the 7/16" tube. So the length of the strap should be 3.7" rather than 3.475"

The aileron throw on sheet 20 indicates 25 degrees up and 20 down. It lists that as 2.5 inches up and 2.0 inches down. if I trig it out it is more like 5.5 and 4.3 inches. Does anybody know which is correct. The aileron horns for the top and bottom wing are also shown on sheet 20 but I could not find any information as to their location. The location on the aileron determines how much travel there is.